May 30, 2003 MOSCOW, Idaho — A University of Idaho-Utah State University research team is the first worldwide to clone a member of the horse family, a mule, according to an article to be published in the journal Science.
The research team includes Gordon Woods, UI professor of animal and veterinary science, Kenneth L. White, Utah State University professor of animal science, and Dirk Vanderwall, UI assistant professor of animal and veterinary science.
The baby mule, Idaho Gem, was born May 4. It is the first clone of a hybrid animal. A mule results from a cross between a female horse, a mare, and a male donkey, a jack. As hybrids, mules are sterile, except in extremely rare cases.
Veterinary examinations of the foal and its surrogate mother showed them to be in good health, Woods said. The foal romped with its surrogate mother during a news conference on the UI campus this morning to announce its birth.
The foal's DNA comes from a fetal cell culture first established in 1998 at the University of Idaho.
As scientifically and commercially significant as their accomplishment is for the horse industry, Woods said he is most excited because the project provides a new animal model, the horse, to advance understanding of human cancer.
Woods believes the breakthrough understanding of cellular biology necessary for horse cloning to proceed may offer new insights into cancer development in humans.
Woods, UI professor of animal and veterinary science, began working on the cloning project in 1998. As director of the Northwest Equine Reproduction Laboratory on the UI Moscow campus, he has spent much of his career studying horse-breeding issues.
Horses present a large challenge to those who would use advanced technology to assist them. Only two "test-tube" horse foals, babies conceived in a test tube, have resulted from in vitro fertilization experiments worldwide.
The mule clone born in May is the full sibling of a champion racing mule owned by Idaho businessman, UI benefactor and mule enthusiast Don Jacklin of Post Falls.
For three years, from 1998 to 2000, the team worked without apparent success. After transferring the nuclei from the mule cells into 134 horse eggs and implanting them into mares, two apparently "false pregnancies" resulted, but both failed to proceed past four weeks.
In 2001, the team began to focus on the calcium levels in the fluid surrounding the eggs during the cloning procedure. The change led to the first fetal heart beat, signifying the team had crossed a significant hurdle in the experiment. That year, researchers transferred 84 eggs, establishing five apparent pregnancies.
"The results were impressive and immediate," Woods said. The first change led to a significant advance in the development of cloned embryos.
In 2002, Woods, White and Vanderwall continued to adjust the calcium levels in the fluid surrounding the egg during the cloning procedure. That change dramatically increased the team's success.
The team established 14 pregnancies using mule DNA in 113 attempts. Eight of the pregnancies continued to at least the 40-day stage when heartbeats were detected.
To test whether mule DNA could be limiting success, the team also made 61 attempts to use horse DNA. The test resulted in seven apparent pregnancies, two of which developed heartbeats. Neither of the horse clone pregnancies developed past the critical 60-day threshold, however.
The UI-Utah State team is the first to succeed among several teams worldwide attempting to clone a member of the horse family. The 2002 preliminary testing showed the method developed by the researchers to successfully clone a mule should work equally as well with a horse, Woods said.
"It basically came down to a matter of numbers, and we wanted to focus most of our attention on cloning a mule, which was our original objective," Vanderwall said.
White is widely recognized as an expert on cattle cloning and brought cloning expertise to the team. Vanderwall, who like Woods, earned doctor of veterinary medicine and Ph.D. degrees, brought extensive clinical expertise to the team.
Woods had taken an interest in basic horse physiology after becoming intrigued by the observation that stallions, male horses, do not develop prostate cancer.
The horse's basic metabolism is "slow" compared to humans and many other mammals, Woods said. He speculated that difference in cellular activity might play a role in both cancer development and reproduction.
He formed an outside company, Cancer2, to investigate that observation with the backing of private investors. The studies showed a fundamental difference between men and stallions in the calcium concentrations within the cells and surrounding fluid. Woods said the team will explore other lines of scientific inquiry opened by this year's success.
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